October 2009

Interesting Planetaries

The Eskimo Nebula, NGC 2392 Planetary nebulas generally make great targets for washed-out astronomers. Most of them standout well even in light polluted skies because they are usually rather small and therefore have relatively high surface brightness. Their small size also means they are best seen using relatively high magnification which helps to darken the background and boost contrast. Finally, planetary nebulas respond very well to narrowband filters, even when observing in urban environments. (Image: Glenn Hitchcock and Bob Cowart/Adam Block/AURA/NOAO/NSF)

Famous planetaries like the Dumbbell Nebula (M27) and the Ring Nebula (M57) are well known to most amateur astronomers and are spectacular objects even in light-polluted skies. But regardless of season there are always planetary nebulas well positioned in the sky for urban observers. Here is a list of good planetaries for washed-out astronomers…


Kruger 60

Triplet of pictures showing Kruger 60's orbital motionKruger 60 is a particularly interesting binary star system in Cepheus. With a short period of only 44.7 years, you can easily see Kruger 60’s PA change about 8 degrees per year. There’s even a convenient nearby reference star that makes the change in PA obvious. Only 13 light years away, Kruger 60 is also one of Earth’s nearest neighbors. Both components are low-mass red dwarfs, but with only 0.18 solar masses, Kruger 60 B is one of the lowest mass stars known. Finally, Kruger 60 B is also a flare star, irregularly doubling in brightness for periods lasting about 5 to 10 minutes. When it flares, it can match or exceed Kruger 60 A in brightness.

Kruger 60, however, is a challenging target for observers in light polluted environments. If you want to take on this challenge, I have more information for you…